Practice projectile for sub-calibre barrels



Dec. 13, 1966 w. LUBBERS 3,291,043

PRACTICE PROJECTILE FOR SUB-CALIBRE BARRELS Filed April 6, 1965 UnitedStates Patent 3,291,048 PRACTICE PRGJECTILE FOR SUB-CALIBRE BARRELSWilli Lubbers, Trittau, Bezirk, Hamburg, Germany, as-

siguor to Nico-Pyrotechnik Hanns-Jurgen Diederichs KG., Hamburg, GermanyFiled Apr. 6, 1965, Ser. No. 445,935 3 Claims. (Cl. 102-41) The presentinvention relates to a practice projectile, particularly for asub-calibre barrel which can be used advantageously, for instance, formortars.

With this practice projectile, particularly good precision in shootingis obtained, since such projectiles, despite the unfavorablecharge-weight ratio, have a particularily small dispersion and a uniformrange.

Ordinarily the mouth of the cartridge case is crimped onto the head ofthe projectile. There results from this a large number of uncontrollableconditions which makes the force necessary to drive the projectile outof the case differ greatly from one projectile to another, or in otherwords, the tamping of the projectile differs greatly and accordinglyalso its dispersion and range.

In accordance with the invention, a very precise fastening of theprojectile in the projectile case is obtained by arranging between therear part of the bi-part type projectile which is located in theprojectile case and the front part of the projectile (projectile head)which extends out of the case an annular flange which acts as supportand is bent over from the front part of the projectile case.

The two parts of the projectile are preferably connected together byscrewing. However, it is, of course, also possible to select some othertype of connection, for instance, a bayonet lock.

In accordance with one special feature of the present invention, anobturator cap is provided between the propellent charge and the rearpart of the projectile, which makes possible a particularly good sealingagainst the smooth bore of the sub-calibre barrel.

By the embodiment in accordance with the invention, the result isobtained that substantially the same forces are required at all times toseparate the projectile from the case, namely, the forces which effect ashearing off of the flanged upper edge of the projectile case.

By the provision of the obturator cap, a uniform action of thepropellent charge is at the same time assured.

In this way, it becomes possible to impart each projectile a lowdispersion and a range which is the same for all projectiles.

One embodiment of the present invention is shown by Way of example inlongitudinal section in the accompanying drawing.

The reference numeral 1 generally designates a subcalibre barrel which,for instance, can have the outer form of a mortar shell and is placed inthe firing barrel of the gun in precisely the same manner as ahigh-explosive shell.

In the lower part of the barrel 1 there is introduced the practicecartridge which consists of the cartridge case 2 and the two parts ofthe bipartite projectile, namely, the front part 3 and the rear part 4.

The cartridge case is advantageously made of light metal or of alight-metal alloy, for instance, of pure aluminum orif the projectilemust be particularly resistant to corrosionof an aluminum-magnesiumalloy.

The bipartite projectile terminates at its rear in an obturator cap 5which can also consist of light metal and the rearward directed sideflange 6 of which rests tightly against the inside of the cartridge caseand subsequently against the inside of the sub-calibre barrel upon theexpulsion of the cartridge as a result of the ignition of the propellentcharge 7, thereby providing a particularly good seal.

The propellent charge 7 is ignited in the customary manner by thestriking of a pin on the percussion cap 8.

Upon the manufacture of the practice cartridges, after the propellentcharge 7 has been introduced, the rear portion or part 4 of the practiceprojectile is introduced, it consisting of a cylindrical piece of metalin the inner axial bore of which a pyrotechnic charge 9, for instance,can be arranged.

The mechanism 10 which serves for the igniting of the pyrotechnic chargeupon the striking of the projectile is unimportant for the descriptionof the invention.

The front widened or counterbored portion 11 of the inner bore of therear part 4 of the projectile is provided with an internal thread 12.

The side wall of the cartridge case 2 which protrudes slightly beyondthe part 4 of the projectile is flanged and forms an inturned flatannular collar or flange 13 which acts as holding ring when the taperedrear portion or coaxially reduced rearward extension 14 of theprojectile head or front part 3 is screwed by means of an outer thread15 on the extension 14 corresponding to the thread 12 into the rearportion 4 of the projectile. The coaxially reduced extension 14 defineswith the rear end portion of the body of the part 3 a fiat, annularshoulder, which is in confronting and cooperating relationship with theforward terminal end of the rear part 4, such end defining a shoulder,and the shoulders being flat and clampingly en gaging the interposedfiat annular flange 13, as can be readily appreciated from the drawing.The flange 13 is tightly interposed between the cooperating shouldersand fixed securely therebetween by virtue of the fastening means whichconnects the parts 3 and 4 together, such fastening means being in thenature of the cooperating internal threads 12 on the wall of the bore 11of the rear part 4 and the external threads 15 on the extension 14 ofthe front part 3.

In conclusion, it should be pointed out that by the embodiment inaccordance with the invention, a particularly good sealing is obtainedbetween the projectile and the cartridge case, since the flanged annularcollar in the form shown in the drawing serves simultaneously as sealingring. This is of particular importance in the case of pyrotechniccompositions, since they readily lose effectiveness as a result of theadmission of moisture. However, it can be appreciated that, due to thefixed interpositioning of the flat flange 13 between the flatcooperating shoulders on the interlocked front and rear parts 3 and 4,when the projectile is fired, the flange 13 will be uniformly shearedoff and, after the shearing, no undesired loose parts will remain.

What is claimed is:

1. A practice cartridge adapted to be inserted into the firing barrel ofa gun comprising a tubular cartridge case having a front end, a two partprojectile including a rear part and a front part, said rear part beingdisposed axially in the case and having a front end formed with an axialbore providing a terminal front end, annular flat shoulder on said rearpart, said front part having a rear end terminating in a coaxiallyreduced rearward extension fitted in the bore of the front end of therear part, said coaxial extension defining with the body of the frontpart at the rear end thereof an annular flat shoulder confronting andcomplementary to the shoulder on the rear part, means securing saidfront and rear parts together in axial alignment and said cartridge casebeing formed at its front end with an inturned annular flat flangetightly interposed between the shoulders and held therebetween by virtueof the means securing said parts together, said flange being disposednormal to the aligned axes of the parts and adapted to be sheared 01fupon firing of the projectile.

2. The invention of claim 1, wherein said means securing the partstogether comprises interlocking means provided on the extension on thefront part and on the wall of the bore in the rear part.

3. The invention of claim 2, wherein said rear part has a rear end, saidcase being formed with a bore, spaced rearwardly from the rear end ofthe rear part and adapted to house a propellant charge, said case beingformed with a chamber intermediate the rear end of the rear part and thepropellant charge and an obturator cap arranged in said chamber andinterposed between the rear end of the rear part and the propellantcharge.

References Cited by the Examiner SAMUEL FEINBERG, Primary Examiner.

ROBERT F. STAHL, Examiner.

1. A PRACTICE CARTRIDGE ADAPTED TO BE INSERTED INTO THE FIRING BARREL OFA GUN COMPRISING A TUBULAR CARTRIDGE CASE HAVING A FRONT END, A TWO PARTPROJECTILE INCLUDING A REAR PART AND A FRONT PART, SAID REAR PART BEINGDISPOSED AXIALLY IN THE CASE AND HAVING A FRONT END FORMED WITH AN AXIALBORE PROVIDING A TERMINAL FRONT END, ANNULAR FLAT SHOULDER ON SAID REARPART, SAID FRONT PART HAVING A REAR END TERMINATING IN A COAXIALLYREDUCED REARWARD EXTENSION FITTED IN THE BORE OF THE FRONT END OF THEREAR PART, SAID COAXIAL EXTENSION DEFINING WITH THE BODY OF THE FRONTPART AT THE REAR END THEREOF AN ANNULAR FLAT SHOULDER CONFRONTING ANDCOMPLEMENTARY TO THE SHOULDER ON THE REAR PART, MEANS SECURING SAIDFRONT AND REAR PARTS TOGETHER IN AXIAL ALIGNMENT AND SAID CARTRIDGE CASEBEING FORMED AT ITS FRONT END WITH AN INTURNED ANNULAR FLAT FLANGETIGHTLY INTERPOSED BETWEEN THE SHOULDERS AND HELD THEREBETWEEN BY VIRTUEOF THE MEANS SECURING SAID PARTS TOGETHER, SAID FLANGE BEING DISPOSEDNORMAL TO THE ALIGNED AXES OF THE PARTS AND ADAPTED TO BE SHEARED OFFUPON FIRING OF THE PROJECTILE.